A function designator or a list whose car is a function designator.
remote-debugging-connection-add-close-cleanup records function as a cleanup in connection. When connection is closed, for whatever reason, each recorded function is invoked (by
funcall for a
symbol, or by applying the car to the cdr for a
list). function is added only if it is not already in the list (tested by
remote-debugging-connection-remove-close-cleanup is needed when you repeatedly create some objects that do not live for long but you still want cleanups for them. In this situation, the cleanup list would grow indefinitely unless you call
remote-debugging-connection-remove-close-cleanup when an object is discarded.
LispWorks User Guide and Reference Manual - 20 Sep 2017